When ships travel up the St. Lawrence Seaway from Montreal to the upper Great Lakes, they climb 180 metres through the locks, the height of a 60-storey building. While most of the Great Lakes and St. Lawrence are clear sailing for big ships, there are five canals along the way to get past shallower areas. The locks allow the vessels to navigate through those areas. 60 years ago, the locks took 22,000 workers, and massive excavations, but it was finished ontime and on budget. In present day, the locks are integrating the use of technology, including a hands-free mooring system, that allow bigger ships to navigate safely through the locks. Each year, the locks see 4,000 transits, about 75 percent of those are by the fleet of lakers.